BRITON'S ONE MONOPOLY.

King Country Chronicle, Volume VII, Issue 585, 16 July 1913, Page 3

BRITON'S ONE MONOPOLY.

The city industry which the British are believed to have exclusively in their own hands 'I:? the production of china clay, Jtisc.i for the manufacture of highly finished paper, in the ceramic arts, and in the textile trade. The greater part, it" not all, of the product now conies from Devonshire and Cotnwall, the latter producing by far the greatest portion. The production is estimated at 2.070,682 tons annually for the two sections, the value being set at £701,500. China clay is believed to be decomposed granite, although scientists differ as to its exact origin. It is usually found in beds shaped like a bowl or basin, between granite hilis, and is covered by what is termed an " "over-burden" which varies in thickness from six feet to 40 feet. A pit is formed by removing the overburden, and a shaft is sunk outside the bed 'in more solid ground conveniently near. A passage called an "adit level," being almost horizontal but sloped enough for drainage, is driven from the shaft into the bed of clay. A stream of water is turned into the top of the pit and run.-; down over the face of the clay. Workmen stamp about in the pit to dislodge the clay, which then Hows in liquid form into a hole in the bottom of the liit through the adit level to the bottom of the shaft, whence it is pumped to th.: sun'aee. Sand, mica, and other impurities in th'' clay are s-.-parated in what is known as u '"mica drag," a tank or basin so arranged that the mica .••Hid other particles fall from the clay proper by force of gravity. The clay is then passed into settling tanks, and from these the water is drawn oiT and the deposit of clay removed to the kiln, where it is dried in blocks. In this form it is shipped to the potteries or other factories using it.—"Popular Mechanics."